Bearing solutions for large horizontal forces

There are two main general bearing arrangements that are applied where transverse horizontal loads on a bridge deck must be resisted, which are discussed in this paper: a guided-sliding and a free- sliding bearing, paired up on one axis (the standard bearing setup for bridges); and a pair of free- sliding bearings designed for vertical loads, and a second pair of free-sliding bearings designed for horizontal loads on a so-called shear key (or wind shoe), or directly on a pylon. Their respective applicabilities, advantages, and limitations are discussed, with special emphasis on cable-supported bridges. For a shear key setup, restraint becomes a central design issue, affecting the installation, exchange and life-cycle cost of the bearings. Causes of restraint loads on such bearings, and solutions such as preloading systems, are discussed. Two case studies, from current major projects, are presented.